Diagnosis and Prediction of Obstructive Sleep Apnea

ABSTRACT

A tongue location monitoring system, including, one or more position circuits that respond to transmissions from a transceiver, a transceiver that transmits to the one or more position circuits, a control circuit coupled to the transceiver; wherein the control circuit determines the location of a person&#39;s tongue based on the responses of the position circuits; and wherein either the transceiver or the position circuits are implanted in the muscle of the person&#39;s tongue or placed on the tongue, and the latter is placed outside the person&#39;s head.

FIELD OF THE INVENTION

The present invention relates generally to a system and method ofdiagnosing and predicting obstructive sleep apnea based on the positionof the tongue muscle.

BACKGROUND OF THE INVENTION

Typically obstructive sleep apnea (OSA) is diagnosed in a sleeplaboratory by attaching the patient to various measurement devices,which measure parameters such as an Electroencephalography (EEG), anElectromyography (EMG) of respiratory muscles, a device for measuringblood Oxygen saturation and devices for measuring other parameters whilethe patient sleeps.

Obstructive sleep apnea is the most common type of sleep apnea. One ofits causes is the collapse of the tongue muscle, wherein the collapsedtongue muscle obstructs the airway and causes an OSA event.

Various devices have been designed to enable diagnosing the occurrenceof OSA without going to a sleep laboratory. One example is a device thatmonitors changes in the peripheral arterial tone as manifested bychanges in the pulsatile arterial blood volume in a terminal extremityof a body part, e.g., a digit (finger or toe) of the subject, asdescribed in U.S. Pat. No. 7,374,540.

Other methods of diagnosing OSA include implantable systems, for examplea system that uses an intra-thoracic pressure sensor that sensesbreathing movements for treating respiratory disorders as described inU.S. Pat. No. 6,572,543. In US patent application publication no. US2008/0103407 a system that senses breathing movements by applying animplantable bio-impedance sensor is described. In US patent applicationpublication no. US 2009/0078274 an electro active polymer metalcomposite sensor is attached to a region in an airway passage of an oralcavity. The electrical output may be wirelessly transmitted to signifyan obstructive sleep apnea event.

Other methods include a contact microphone that detects sounds and/orVibrations, and yet other methods include temperature sensors thatdetect temperature changes when an obstructive sleep apnea event occursthat result from the event.

Upon detection of the occurrence of the OSA event various remedialmeasures can he taken, for example activating an implanted stimulator oran external device.

SUMMARY OF THE INVENTION

An aspect of an embodiment of the invention, relates to a system andmethod for diagnosing and predicting an OSA event by monitoring thelocation of the tongue muscle. In an exemplary embodiment of theinvention, a reader is placed outside a patient's head and one or moreposition circuits are placed on the patient's tongue or implanted in thetongue. Optionally, the reader transmits signals to the positioncircuits and receives a signal back from the position circuits. Thereturned signal is used to determine the location of the positioncircuits relative to the reader. Optionally, the reader repeatedlyqueries the position circuits, so that it can monitor the motion of thetongue muscle.

In some embodiments of the invention, the position circuits are passiveRFID tags. Alternatively, the position circuits may be active RFD tags,BT Transceivers, WiFi transceivers or any other type of wirelesstransmitters/receivers. In an exemplary embodiment of the invention, theposition circuits are implanted directly into the tongue muscle.Alternatively, the position circuits are embedded in an implantableencasement that provides other functions such as to stimulate the tonguemuscle.

In some embodiments of the invention, the position circuits are embeddedin an adhesive biodegradable tape that can be placed on the patient'stongue before going to sleep. Optionally, while the patient is sleepingthe position circuits will accept transmissions from the external readerand reply to the transmissions. In an exemplary embodiment of theinvention, after a predetermined time the tape will degrade and theposition circuits will exit through the digestive system.

In some embodiments of the invention, the position circuits are placedin the external reader. Optionally, the reader wirelessly transmitspower to an implant in the patient's tongue and the implant transmits asignal to the position circuits.

In some embodiments of the invention, the reader determines the locationof the position circuits and optionally monitors the motion of theposition circuits. Optionally, the reader stores the information in anon-volatile memory for analysis at a later date, for example by apractitioner on a computer to diagnose the patient. Alternatively oradditionally, the reader may transmit instructions to an implant or toother devices to act upon the information, for example to stimulate thetongue muscle when sensing that an USA event is about to occur andprevent it from occurring.

There is thus provided according to an exemplary embodiment of theinvention, a tongue location monitoring system, comprising:

one or more position circuits that respond to transmissions from atransceiver;

a transceiver that transmits to the one or more position circuits;

a control circuit coupled to the transceiver;

wherein the control circuit determines the location of a person's tonguebased on the responses of the position circuits; and

wherein either the transceiver or the position circuits are implanted inthe person's tongue or placed on the tongue, and the latter is placedoutside the person's head.

In an exemplary embodiment of the invention, the position circuits areimplanted in the tongue muscle. Optionally, the transceiver is implantedin the tongue muscle. In an exemplary embodiment of the invention, theposition circuits are embedded in an implantable stimulator that isimplanted in the tongue muscle and the implantable stimulator is adaptedto stimulate the tongue muscle. Optionally, the position circuits areembedded in a biodegradable tape that is adhesively attached to thetongue. In an exemplary embodiment of the invention, the control circuitdetermines the location of the tongue based on the travel time of thesignal to the position circuit and back. Optionally, the control circuitdetermines the location of the tongue based on the strength of thesignal returning to the transceiver. In an exemplary embodiment of theinvention, an obstructive sleep apnea event is detected by monitoringthe location of the tongue. Optionally, an obstructive sleep apnea eventis detected by monitoring the angle of arrival of a response signal fromthe position circuits. In an exemplary embodiment of the invention, theposition circuits are queried sequentially. Alternatively, the positioncircuits are queried in parallel. Further alternatively, the positioncircuits are queried continuously. Further alternatively, the positioncircuits are queried periodically. In an exemplary embodiment of theinvention, the transceiver is provided power wirelessly and thetransceiver queries the position circuits as long as it is providedpower wirelessly.

There is further provided according to an exemplary embodiment of theinvention, a method of monitoring the location of the tongue,comprising:

positioning either a transceiver or one or more position circuits asimplants in a person's tongue or on the tongue, and positioning thelatter outside the person's head;

transmitting signals from the transceiver to the position circuits;

receiving a response from the position circuits;

calculating the location of the position circuits relative to thetransceiver from the response;

determining if an obstructive sleep apnea event is about to occur basedon the calculated locations.

In an exemplary embodiment of the invention, the position circuits areimplanted in the tongue or on the tongue. Alternatively, the positioncircuits are positioned outside the head. In an exemplary embodiment ofthe invention, the muscle of the tongue is stimulated responsive to thedetermining.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and better appreciated from thefollowing detailed description taken in conjunction with the drawings.Identical structures, elements or parts, which appear in more than onefigure, are generally labeled with the same or similar number in all thefigures in which they appear, wherein:

FIG. 1 is a schematic illustration of a patient's head with a tonguelocation monitoring system, according to an exemplary embodiment of theinvention;

FIG. 2 is a schematic block diagram of a tongue location monitoringsystem with a reader and an implant with position circuits embeddedtherein, according to an exemplary embodiment of the invention;

FIG. 3 is a flow diagram of the process of monitoring the position ofposition circuits, according to an exemplary embodiment of theinvention;

FIG. 4 is a schematic block diagram of an alternative tongue locationmonitoring system with a reader and implant, according to an exemplaryembodiment of the invention;

and

FIG. 5 is a schematic block diagram of a tongue location monitoringsystem with a reader and a biodegradable tape with position circuitsembedded therein, according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION

The present disclosure incorporates by reference U.S. patent applicationSer. No. 12/581,907 tiled Oct. 20, 2009 by the instant inventor, thedisclosure of which is incorporated herein by reference describing asmall implantable stimulator for dealing with an OSA event.

FIG. 1 is a schematic illustration of a patient's head 105 with a tonguelocation monitoring system 100, according to an exemplary embodiment ofthe invention. In an exemplary embodiment of the invention, system 100includes an implant 110 implanted in the muscle of a patient's tongue140, and an external reader 150 (for a non-limiting example, an adhesivepatch that is attached to the patient's cheek or neck). Optionally, theimplant 110 includes one or more position circuits 120 that enablereader 150 to locate the distance and/or angle and/or position to theposition circuits 120 and monitor their relative position. In someembodiments of the invention, position circuits 120 may be radiofrequency identification tags (RFID tags) placed in implant 110.Alternatively, position circuits 120 may be implanted independently inone or more locations in the muscle of the patient's tongue. Optionally,the distance between the position circuits 120 may be a pre-selectedvalue enforced by the encasement of implant 110 or may be a randomvalue. The position circuits 120 can comprise one or more circuits. Theposition circuits 120 can be passive or active. Passive positioncircuits 120 may comprise RFID tags, induction tags and the like.Passive position circuits 120 may comprise devices which emit energy inresponse to the presence of predetermined energy. Active positioncircuits 120 may comprise a Bluetooth device, a WiFi device, a poweredRFID tag and the like. Active position circuits 120 may comprise deviceswhich transmit a signal capable of being received by a receiver, such asreader 150.

In some embodiments of the invention, position circuits 120 may bepassive circuits with or without an internal power source that respondto an external signal without requiring an internal power source.Alternatively, position circuits 120 may be active transmitters using aninternal power source to function, for example an active RFID tag, aBluetooth transmitter, a WiFi transmitter, or other types oftransmitters.

In an exemplary embodiment of the invention, reader 150 is positionedoutside of the user's head 105, for example in the form of a patch thatcan be adhesively attached to the patient's neck, cheek or below thepatient's jaw, or to the vicinity thereof. Optionally, reader 150 may bein the form of a necklace or a necktie or other wearable items to makeit less conspicuous.

FIG. 2 is a schematic block diagram of tongue location monitoring system100 including reader 150 and implant 110 with position circuits 120embedded therein, according to an exemplary embodiment of the invention.Optionally, reader 150 is adapted to transmit and/or receive signalsfrom position circuits 120 and determine from the transmissions arelative position of the tongue muscle. In some embodiments of theinvention, the position is determined based on the travel time of thesignal to position circuits 120 and from position circuits 120 to reader150. Alternatively, other methods known in the art are used to determinethe location of position circuits 120 relative to reader 150 asdescribed below.

In an exemplary embodiment of the invention, reader 150 includes atransceiver 152 that transmits and/or receives signals to/from positioncircuits 120. In some embodiments of the invention, position circuits120 are RFID tags, which respond to a specific signal. Optionally,position circuits 120 are relatively small so that they can easily beimplanted in the tongue muscle, for example some RFID circuits aresmaller than 0.05 mm X 0.0 5mm. In some embodiments of the invention,position circuits 120 are placed inside implant 110, which providesadditional functions, for example stimulating the tongue muscleresponsive to internal or external instructions. Optionally, implant 110includes a control circuit 130 to provide the additional functions (e.g.stimulation, or communications with other external devices). In someembodiments of the invention, determination of the location of theposition circuits 120 can be used to more accurately determine thelocation of implant 110, for example based on the location of multipleposition circuits 120.

in an exemplary embodiment of the invention, reader 150 includes a powersource 154 (e.g. a battery) and an activation switch 159. Optionally,reader 150 also includes a control circuit 156 and a memory 158 tocontrol reader 150. Optionally, control circuit 156 includes a processorand is programmed to instruct transceiver 152 to transmit a specificsignal for each position circuits 120, receive a response to thetransmitted signal and calculate the distance based on the transmission.

In some embodiments of the invention, reader 150 includes a motionsensor 145. Motion sensor 145 is preferably coupled to control circuit130. Motion sensor 145 can be an accelerometer, gyroscope, or any otherdevice capable of indicating the implant 110 has changed its position,and optionally the directional vector of such change.

In some embodiments of the invention, calculation of the distance isbased on the signal strength. Alternatively or additionally, thecalculation is based on the travel time of the signal to positioncircuits 120 or the time for the round trip of the signal to positioncircuits 120 and back to reader 150. Optionally, when reader 150 isinitially activated it is calibrated relative to position circuits 120assuming that the tongue muscle is in a normal state. Optionally, theuse of multiple position circuits 120 positioned at pre-selectedlocations relative to each other allows more accurate three-dimensionaldetermination of the location of position circuits 120 relative toreader 150.

in an exemplary embodiment of the invention, an increase in distancebeyond a threshold value in pre-determined directions will be anindication of an OSA event. In other exemplary embodiment of theinvention, a decrease in distance beyond a threshold value inpre-determined directions will be an indication of an OSA event.

In some embodiments of the invention, the angle of arrival may be usedto determine an OSA event. Optionally, reader 150 is calibrated uponactivation to an initial angle between the reader and the positioncircuits 120. Optionally, a change in the angle of arrival of the signalthat indicates movement of the tongue muscle toward the patient's backbeyond a threshold value will indicate an OSA event.

In some other embodiments of the invention, the time of arrival (TOA) ofthe signal from the position circuits 120 to the reader 150 may indicatean OSA event. In some embodiments of the invention, the signal strengthreceived by the reader 150 may indicate an OSA event. In some otherembodiments of the invention, the signal strength correlated with TOA ortime of travel, between the position circuit 120 and the reader 150,received by the reader 150 may indicate an USA event. In someembodiments of the invention, the first detected signal received by thereader 150 after the activation of the position circuits 120 mayindicate an OSA event.

In the previous examples, each indication noted as an indication of anOSA event may also be considered as a precursor or the onset of an USAevent. Thus, the present indications may provide an indication that anOSA event is likely to occur. In some embodiments of the presentinvention, any one or any combination of the above indications can beused to indicate the onset or the occurrence of an OSA event. Suchindications or any combination thereof can also he reviewed post an OSAoccurrence such that the control circuit 130 is reprogrammedautomatically post an OSA event to identify the sequence of indicationsleading to an OSA event that occurred with the specific patient.

FIG. 3 is a flow diagram 300 of the process of monitoring the positionof position circuits 120, according to an exemplary embodiment of theinvention. In an exemplary embodiment of the invention, reader 150 sends(310) a signal to position circuits 120. Optionally, if there is morethan one position circuit 120 reader 150 may query the position circuits120 sequentially or in parallel. In some embodiments of the invention,each position circuit 120 accepts a signal representing a different codeand each position circuit 120 only responds to signals with its code.Alternatively, all the position circuits 120 accept the same code.

In an exemplary embodiment of the invention, the position circuits 120respond (320) to the signal from reader 150. In some embodiments of theinvention, each position circuit 120 responds with a differentpre-selected delay time relative to the signal from reader 150, so thatreader 150 will receive the responses one after another even if all theposition circuits 120 receive the signal simultaneously.

In an exemplary embodiment of the invention, control 156 of reader 150processes the responses from position circuits 120 and calculates (330)from the responses the relative location of each position circuit 120.Optionally, control 156 takes into account pre-selected delay times andif the position circuits are positioned with a non-varying distance orif their relative position is variable. In an exemplary embodiment ofthe invention, control 156 stores the details of the position in memory158 and keeps track of the current position relative to the previouspositions based on previous readings.

Optionally, control 156 can then determine (340) if an OSA event isabout to take place, for example if the tongue muscle is collapsing sothat it will block the airway. Optionally, control 156 can thendetermine (340) if an OSA event is about to take place based on thetrajectory of the position circuits 120. Optionally, control 156 canthen determine (340) if an OSA event is about to take place based on oneor more indications as described here in above in conjunction with thedescription of FIG. 2, whether or not the indications were received inresponse to a signal sent to the position circuits 120.

Optionally, in step 340 the reader 150 can determine if an onset of anOSA event is likely, or if an OSA event has occurred in the past basedon the various indications received. In an exemplary embodiment of theinvention, as long as an OSA event is not about to occur, reader 150will continue to query position circuits 120. In some embodiments of theinvention, the querying is performed continuously. Alternatively, thequerying may be performed periodically, for example 1000 times a secondor 100 times a second. In some other embodiments of the invention, thereader will not query the position circuits, and the position circuitswill continuously send indication or emit energy in response to whichthe reader 150 can determine the position of position circuits 120.

In some other embodiments of the present invention, the motion sensor145 located in the implant 110 activates the position circuits 120 whichin response emit energy or transmission upon in response to which thereader may determine the position of the position circuits 120.

In some embodiments of the invention, transceiver 152 transmits thesignal from multiple positions along the length of reader 150.Optionally, the location of position circuits 120 are determined bycomparing the timing of the responses or through an analysis of any oneor more of the indications disclosed herein above.

In an exemplary embodiment of the invention, if reader 150 determinesthat an OSA event is about to take place (340) it may take (350) variousremedial actions, for example notify an implanted stimulator (e.g.implant 110) to stimulate the muscle and prevent it from occurring.Alternatively or additionally, reader 150 may include a buzzer (notshown) that provides an audible or tactile alarm to alert the patient tothe occurrence of an OSA event, for example in the diagnostic stage oftreating the patient. Optionally, reader 150 records informationregarding the occurrence of an OSA event in its memory 158, for examplethe time and date of the occurrence. In some embodiments of theinvention, reader 150 may be connected either during usage or afterusage to a computer to analyze data stored in memory 158. Optionally,reader 150 may record a sequence of indications leading to an OSA eventin memory 158. Optionally, reader 150 may further in step 350 reprogramitself to identify a future OSA event or the onset of such an eventbased on previous sequences of events which led to an OSA event.Optionally, memory 158 may be a non-volatile memory so that the data isavailable even if power source 154 is depleted. In some embodiments ofthe invention, memory 158 is removable and can be read using a memorycard reader, for example with a USB memory card reader.

In some embodiments of the invention, reader 150 is initially calibratedwhen it is first deployed, for example by requiring the patient to pushhis tongue forward and/or back during the first few minutes fromactivation, so that reader 150 can record the extreme possible locationsoccurring as a result of natural use of the tongue and use the data tocompare with locations occurring later that result from muscle collapseduring an OSA event.

In some embodiments of the invention, reader 150 is designed to be ableto record a response from position circuits 120 in allowable orpreapproved positions, when the tongue muscle is functioning.Optionally, if the tongue muscle collapses, position circuits 120 moveout of range and reader 150 does not receive a response. In an exemplaryembodiment of the invention, reader 150 determines if an OSA event isabout to occur, based on the previous motion of position circuits 120,and optionally also from the fact that position circuits 120 stoppedresponding. Optionally, reader 150 may signal implant 110 to stimulatethe tongue muscle, causing the tongue to return to its correct positionand communications from position circuits 120 to resume.

In some embodiments of the invention, implant 110 may monitor thecommunications with position circuits 120 and if the communicationscease since position circuits 120 are out of range, implant 110 willstimulate the tongue muscle without receiving an instruction from anexternal source. Alternatively, reader 150 may have separatecommunication systems for communicating with position circuits 120 and aseparate communication system for communicating with implant 110.Optionally, the communication system for communicating with implant 110has a greater range than the communication system for communicating withposition circuits 120, so that if communications with position circuits120 fail reader 150 can still provide instructions to implant 110 totake remedial actions.

FIG. 4 is a schematic block diagram of an alternative reader 450 andimplant 410, according to an exemplary embodiment of the invention.Optionally, reader 450 includes a control 456, a memory 458 similar tothe elements of reader 150. However in reader 450 in contrast to reader150, position circuits 120 are embedded in reader 450 outside of thepatient and not embedded in implant 410 that is embedded inside thetongue muscle of the patient. Optionally, reader 450 includes a powersource 454 and a transceiver 452 that is adapted to wirelessly transmitpower to tracking object 410. In an exemplary embodiment of theinvention, implant 410 includes a control circuit 430, a transceiver 414and a power receptor 412. Optionally, transceiver 452 transmits powerwirelessly to power receptor 412. In an exemplary embodiment of theinvention, when tracking object 410 begins to receive power from reader450, transceiver 414 transmits signals to locate position circuits 120.Optionally, if the link is broken and tracking object 410 ceases toreceive power from reader 450; it stops transmitting a signal forposition circuits 120 and control circuit 430 may instruct implant 410to stimulate the tongue muscle of the patient. In some embodiments ofthe invention, control circuit 430 will only stimulate the patient ifthere is a determination that the position of the tongue muscle ismoving in a direction that will cause an OSA event. Optionally, if powersource 454 of reader 450 is running low, for example below 10% left, itwill notify tracking object 410 to shut off the stimulator.

In some embodiments of the invention, multiple readers 150 are used tomonitor the location of position circuits 120, for example one readermay be positioned on the patient's cheek and the second reader under thepatient's chin. Optionally the multiple readers 150 communicate witheach other via transceiver 152, for example to compare the responsesreceived from position circuits 120. In some cases one may receive aresponse from a specific position circuit 120 while the other does notdue to the position of the tongue muscle. Optionally, implant 110 may beinstructed to stimulate the tongue muscle only if there is a loss of asignal from more than one reader or only if all readers 150 don'tprovide a signal. Alternatively, implant 110 may be instructed tostimulate the tongue muscle if a single reader 150 doesn't provide asignal. Optionally, implant 110 may be instructed to stimulate thetongue muscle based on additional information, for example thetrajectory of motion of the tongue.

In an exemplary embodiment of the invention, reader 150 may includeadditional sensors, for example:

1. Sensors that provide surface EMG to detect movement of the tongue;

2. Sensors that provide ultrasound imaging of the tongue and itslocation;

3. Sensors that provide infrared imaging to sense temperature changes;

4. Sensors that provide temperature measurements to detect changes intemperature due to decreased breathing;

5. A contact microphone to detect vibrations due to snoring andobstruction of the air path;

6. A contact microphone to record breathing sounds;

7. Sensors that provide ECG measurements;

8. Sensors that provide EEG measurements;

9. Sensors that sense heart rate variability;

10. Sensors that measure oxygen saturation;

11 Sensors that measure movement;

12. Sensors that measure motion; and

13. Sensors that measure vector acceleration.

Optionally, reader 150 may incorporate any of the above measurements toenhance accuracy of the diagnosis and prediction of an OSA event.

FIG. 5 is a schematic block diagram of a tongue location monitoringsystem 500 with a reader 550 and a biodegradable tape 510 with positioncircuits 520 embedded therein, according to an exemplary embodiment ofthe invention.

Optionally, reader 550 is similar to reader 150 by including a control556, a memory 558, a power source 554, an activation switch 559 and atransceiver 552. Optionally, biodegradable tape 510 is a biocompatibleadhesive tape that is dissolvable, for example when in contact with thepatient's saliva it dissolves within a few hours (e.g. between 1-8hours; during the patient's sleep). Optionally, different tapes may beused with different lifetimes before being completely dissolved. In anexemplary embodiment of the invention, position circuits 520 (e.g. anRFID circuit) embedded therein are coated with a biocompatible enclosure530 that is resistant to digestive fluids. Optionally, during thepatient's sleep tape 510 dissolves and position circuits 520 areswallowed and later extracted through the digestive system. In anexemplary embodiment of the invention, a constant distance 540 is setbetween each position circuit 520. Alternatively, position circuits 120may be positioned randomly on tape 510.

In an exemplary embodiment of the invention, biodegradable tape 510 isattached to a patient's tongue before going to sleep. Optionally, reader550 is attached to the patient's head 105, or positioned or worn by thepatient near his head 105, so that the transmissions from reader 550will be received by position circuits 520 on tape 510. Optionally,reader 550 is activated and monitors the position of the patient'stongue during his/her sleep by transmitting signals to position circuits520 as described above.

In an exemplary embodiment of the invention, the location data is storedin memory 558 to be taken out later and analyzed by a computer todiagnose obstructive sleep apnea. Alternatively or additionally, thedata may be transmitted live by reader 558 to an external computer usinga wireless connection (e.g. BT or WiFi or a cellular wan connection). Insome embodiments of the invention, reader 558 is connected with a datacable to a computer (e.g. using a USB connection) to transmit the datawhile it is being collected. Optionally, the data is encrypted,compressed or manipulated by other methods (e.g. error correctionschemes) to ensure its safe delivery to the correct target. Optionally,the data recorded by reader 558 may be used to determine if implantationof a stimulator is feasible for the patient. Additionally, the datarecorded by reader 558 may be used to initially program an implantablestimulator based on the measurements, for example programming theintensity of stimulation based on the degree of collapse of the tonguefor the specific patient.

In some embodiments of the invention, other measured data is combined tothe data collected by reader 558, for example ECG or EEG data, toenhance the accuracy of the measurements.

In an exemplary embodiment of the invention, position circuits 520 mayinclude surface EMG (electromyography) electrodes. Optionally, theelectrodes sense EMG data from the tongue muscle and transmit the datato reader 558 with the other data from position circuits 520 (e.g. RFIDtag ID information).

It should be appreciated that the above described methods and apparatusmay be varied in many ways, including omitting or adding steps, changingthe order of steps and the type of devices used. It should beappreciated that different features may be combined in different ways.In particular, not all the features shown above in a particularembodiment are necessary in every embodiment of the invention. Furthercombinations of the above features are also considered to be within thescope of some embodiments of the invention.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather the scope of the present invention isdefined only by the claims, which follow.

1. A tongue location monitoring system, comprising: one or more positioncircuits that respond to transmissions from a transceiver; a transceiverthat transmits to the one or more position circuits; a control circuitcoupled to the transceiver; wherein said control circuit determines thelocation of a person's tongue based on the responses of the positioncircuits; and wherein either the transceiver or the position circuitsare implanted in the person's tongue or placed on the tongue, and thelatter is placed outside the person's head. 2-18. (canceled)